Machine tool



Aug. 25, 1959 Filed May 29, 1958 P. J. ROBISCHUNG 2,900,766

MACHINE TOOL 2 Sheets-Sheet 1 INVENTOR.

PHILIP .J. ROBISCHUNG BY [0% BWMQ ATTORNEYS Aug; 25, 1959 P. J.ROBISCHUNG 2,900,766

. MACHINE TOOL Filed May 29, 1958 2 Sheets-Sheet 2 INVENTOR.

PHlUP 1 J. RDBLSCHUHG ATTORNEYS 2,900,766 Patented Aug. 25, 1959 MACHINETOOL Philip J. Robischung, Kalamazoo, Mich., assignor to HammondMachinery Builders, Inc., Kalamazoo, Mich, a corporation of MichiganApplication May 29, 1958, Serial No. 738,869

4 Claims. (Cl. 51-448) This invention relates to an apparatus foreffecting a controlled mechanical force at a desired point and itrelates particularly to interchangeable means for applying either aspring or a fluid pressure created force onto a tensioning pulley of abelt-type abrading machine. An example of the type of machine to whichthe present invention is especially applicable is found in Us. PatentNo. 2,612,007 assigned to the assignee of the present invention.

While the present invention was developed particularly out of a desirefor belt-tensioning means in a belt-type abrading machine, of the typeabove indicated, by which 2 means the tensioning force could be eitherspring or fluid pressure, as desired, it will be recognized that thestruc ture of the invention can be applied to a wide variety of otheruses. Accordingly, while the invention is hereinafter illustrated anddescribed in terms of a belt-type abrading machine, it will berecognized that such specific reference is for illustrative purposesonly and is not limiting. I

In the use of belt-type abrasive machines, it is necessary to have somedevice, often a pulley, bearing against the belt for holding acontrollable tension thereon. Some installations prefer to apply to suchdevice a mechanically, as spring, created force for effecting such belttension, and other installations employ a pressure fluid, such ascompressed air, to create such belt-tension.

The choice of these alternate sources of tension is primariiy a matterof economics. It is generally recognized that air tensioning providessuperior operation in that a greater tensioning force can beconveniently obtained and the force can be applied more smoothly, butthe spring tension often is acceptable and involves much less cost.Thus, for otherwise identical machines, some customers will specify airtensioning of the abrasive belt whereas other customers will specifyspring tensioning. In order to minimize inventory requirements in themanufacturing plant, it becomes desirable to design the machines so thatthey are as nearly identical as possible, whether air tensioned orspring tensioned, whereby the adaptation of a given machine to one orthe other type of tensioning can be made very simply by only a few stepswhich can be carried out at the extreme end of the manufacturingoperation. In this manner the machines can be built practically to thepoint of completion and held in inventory. When a customers order isreceived, an appropriate unit can then be quickly completed by only afew steps in Y which such unit is adapted for air tensioning or springtensioning as specified by the customer.

Thus, it has long been desirable to provide a construction by which thiselection can be made in the final stages of the manufacturing of a givenmachine and appropriate apparatus installed into such machine inaccordance with a given customers order.

Further, it often happens that the machine is sold with one typeoftensioning apparatus and subsequently, during its useful life, theconditions, as above discussed, under which it operates change and it ispreferred to'have a different type of belt-tensioning means utilized, inwhich case it is desirable that the belt-tensioning means be readilycapable of modification from one type of belttensioning device to theother type thereof.

Accordingly, a principal object of the invention has been to providebelt-tensioning means for a belt-type abrasive machine which can bereadily changed from spring-type tensioning apparatus to pressure-fluidtype apparatus, or vice versa, at a point late in the manufacturingoperation of a given machine or even after the machine is completed andinstalled at the users premises.

A further object of the invention has been to provide apparatus, asaforesaid, in which the conversion from one type of belt-tensioningapparatus to another type of such apparatus can be carried out quickly,easily, by ordinary workmen and by the use of ordinary tools.

A further object of the invention has been to provide apparatus, asaforesaid, in which structure adaptable to either type of tensioningmeans is built into the basic structure of the machine and is merelyprovided with different and easily installed fittings to render it ofone operating type or the other.

A further object of the invention has been to provide apparatus, asaforesaid, in which a portion of the belttensioning apparatus alsofunctions as a structural strengthgiving part of the machine frame.

A further object of the invention is to provide apparatus, as aforesaid,which in either of its possible arrangements provides a structure ofsubstantially greater strength than is normally obtainable frompresently known designs and wherein said additional strength can beobtained without appreciable additional cost.

A further object of the invention has been to provide apparatus, asaforesaid, in which the conversion from one type of tensioning means tothe other type thereof can be carried out without removing parts otherthan the upper pulley assembly and belt from their respective op erativepositions.

. A further object of the invention has been to provide apparatus, asaforesaid, in which the parts will operate as effectively for eitherspring tensioning or pressure-fluid tensioning as is at presentcustomarily obtained by apparatus directed solely to one of said twobelt-tensioning types of operation.

Other objects and purposes of the invention will be apparent to personsacquainted with devices of this general type upon reading thefollowingspecifications and inspection of the accompanying drawings.

In the drawings:

Figure l is a broken rear view of a belt-type abrading machine withtensioning apparatus embodying the invention installed therein.

Figure 2 is a sectional view taken along the line IIII of Figure l andshowing a central sectional view of the abrading machine in Figure 1 andthe spring-type belttensioning apparatus installed therein.

Figure 3 is a section taken along the line III-III of Figure 1. V v 1Figure 4 is a fragmentary showing corresponding to the Figure 1 andillustrating the installation of pressure-fluid type tensioning meansaccording to the invention.

' General description In general, the invention comprises providing agenerally cylindrical housing rigidly within a frame structuresupporting the pulleys over which the abrading belt travels. Said framestructure may advantageously be built with the cylinder rigidly casttherein. A piston extends into said cylinderand provides a mounting basefor one of the belt-supporting pulleys. Adjustable resilient meansare'provided for hearing against said piston within said cylinder formechanical tensioning thereof. Alternatively, the piston above-mentionedis replaceable by a piston 3 of slightly different design, the cylinderclosed and pressure-fluid source means provided for applying therequired pressure to said last-named piston and thence to thebelt-carryingpulley.

Detailed description For the purpose of convenience in description,certain terminology will be used which will be understood to be forconvenience only and not limiting. For example, the terms upward anddownward and derivatives thereof will refer'to directions with respectto the machine in its normal position of operation and/or as shown inthe drawings. The terms forward and rearward and derivatives thereofwill refer respectively to positions toward and away from the operatorsside of the machine. The terms leftward and rightward and derivativesthereof will refer to directions as appearing in individual drawingswhich may be under discussion when said terms are used and,particularly, reference to the rearward side of the machine refers tothe side which appears as leftward in Figure 2. Lastly, the terms inwardand outward and derivatives thereof will refer respectively todirections toward and away from the geometric center of the apparatus.

Referring now to Figure 1, a generally rectangular box-like, framestructure 1 only partially shown, but of known type, is provided forsupporting pulleys 2- and 3 in any suitable manner for carrying anabrasive belt 5. The frame 1 is supported in any convenient manner wellknown to the art and not shown here. A yoke 4 has an opening 4a thereinwhich receives a stem at the upper end of the piston 6 which may then berigidly fastened to said yoke by a suitable pin 60. A guide 7 isreceived between a pair of blocks, of which one appears at 8, foradjusting the yoke 4 about the axis of the piston 6, whereby the axis ofthe pulley 3 is placed as close as possible into parallelity with theaxis of the pulley 2 for reasons which are well known in the industry.

An upper plate 11 extends across the upper end of the frame structure 1and in this particular embodiment of the invention, said upper plate 11is cast integrally with said frame structure 1. An opening 12 isprovided through said upper plate 11 coaxial with the opening 4a andnormally substantially concentric with an axis passing through thegeometric center of the frame structure l. A cylinder 13 extends downwarly from the plate 11 and supports a hollow box 14 at the lower endthereof. Said box is fixed rigidly to the walls 16 and 16a of. the framestructure 1. Said cylinder 13 and the box 14 are all preferably providedby casting same integral with the upper plate 11 and the walls 16 and16a of the frame 1 with which they are associated. The rearward side ofthe box 14 is open but may be closed by a bolted-on plate as will appearmore fully hereinafter. A platen 21 is provided at the front of theframe.

The lower end of the box 14 has a boss 17 provided thereon through whichextends an opening 18 which may, if desired, be lined with suitablebearing material and through which rotatably extends the shaft 19. Acollar 21 holds said shaft 19 against upward movement and a bevel gear22 is mounted for rotation with said shaft and holds it against downwardmovement. A further shaft 23 extends through an opening 24 in the wall16, carries a bevel gear 26 for rotation therewith and also carries thecrank structure 27 for manual rotation thereof. The bevel gears 22 and26 are meshed with each other.

The piston 6 is counterbored to provide a central chamber 28 therein. Aspring 29 is received within said central chamber 28 and is held thereinby the nut31. Said nut is threadedly engaged with the shaft 19 so thatrotation of said shaft effects an axial movement of said nut and therebyadjusts thetension on the spring 29. Diametric and elongated slots 32and 33 are provided through the sides of the piston 6 for reception ofthe 4 1 heads of screws 34 and 36, which screws are received fixedlyinto the nut 31. The heads of said screws being in the slots 32 and 33prevent relative rotation of said nut with respect to said piston.

A further slot 37 (Figure 2) is provided in the outer surface of thepiston 6 and a threaded opening 38 is provided in the cylinder 13 inradial register therewith. A screw 39 is threaded into said opening 38and extends into the slot 37 for limiting the upward and down wardtravel of the piston 6 with respect to the cylinder If desired, a groove40 may be provided around the external periphery of the piston 6 forlubrication purposes, lubricant being supplied thereto through asuitable opening provided with a fitting 45 (Figure 1).

Thus, manual rotation of the crank 27 acts through the bevel gears 26and 22 to rotate the shaft 19 and thereby move the nut 31 axiallyupwardly or downwardly. This tightens or relieves the tension on thespring 29 and thereby adjusts the force by which said spring urges thepiston 6 upwardly and this in turn applies an adjustable mechanicallyresilient force onto the pulley 3 for tensioning the belt 5.

Turning now to the pressure fluid responsive mechanism, attention isdirected to Figure 4 wherein the parts corresponding to the partsalready disclosed and described in connection with Figures 1 through 3are provided with the same numbers as appearing in Figures l to 3. Here,however, the piston 6, the nut 31, the shaft 19, the bevel gears, thehand wheel and other incidental screws, nuts, washers and similar partsassociated with each thereof are all removed and replaced by thepressure fluid responsive devices now to be described. These include apiston 41 taking the place of the piston 6 and a pressure sealingdiaphragm 42, as a common piston leather. A screw 43 and washer 44 holdsaid pressure sealing device firmly against the end of the piston 41.The cylinder is closed by a partition 46 having a peripheral groove forreceiving the lower end of the walls defining the cylinder 13. Anopening 48 extends through the partition for the introduction andremoval of pressure fluid into and from the space between the partition46 and the sealing diaphragm 42. The partition 46 is held in placemerely by a bolt 49 extending partially into the opening 18 andtightened into position by a nut 51. A gasket 52 may be provided ifdesired between the lower end of the cylinder 13 and the adjacent wallof the partition 46. A suitable conduit 53 is connected into the opening48 for the introduction of pressure fluid through said opening andremoval of pressure fluid therefrom.

It will be recognized that the conversion of the apparatus from one formof tensioning mechanism to the other form can be done quickly withoutthe use of special tools, by ordinary maintenance personnel and withoutseriously disturbing the other parts of the abrading machine. Forexample, in removing the spring tensioning apparatus, it is necessaryonly to remove the piston 6 and the parts associated therewith, togetherwith the shaft 19, the bevel gears and the handle 27 all of which arereadily accessible and can be easily removed. While it is necessary toremove the belt from the pulleys in order to render the yoke 4 and thepiston 6 capable of moving upwardly out of the cylinder 13, this can bereadily accomplished inasmuch as the belt and the pulleys are alsoeasily accessible. reached through the back of the machine, loosenedfrom their respectiveshafts and then removed through the back of themachine after said shafts are withdrawn. When these parts are removed,the piston 41 is then placed into the opening 4a of the yoke 4 andslipped into the cylinder 13. The cylinder 13 and the box 14 associatedtherewith are not disturbed in any respect nor in any other part of theframe of the machine nor is the lower pulley. The partition 46 can beinserted through the back of the machine and through the opening in theback of the box 14. The screw 49 and the nut 51 can also be inserted Thebevel gears can be,

through the back of the box 14 and the nut 51 then suitably tightened.The plate 15 may in this case be omitted or if used it may be providedwith a suitable opening for the passage of the conduit 53. Otherwise,said conduit, as shown in Figure 4, may be passed through the shaftopening 24. I

While the specific embodiment of the invention has been utilized hereinfor illustrative purposes, it will be recognized that the invention maybe embodied in a wide variety of specific devices and, accordingly, thehereinafter appended claims will be interpreted to include such otherdevices excepting as said claims, by their own terms, may expresslyrequire otherwise.

What isclaimed is:

1. In a belt-tensioning apparatus for a belt-type abrading machine, thecombination comprising: a movable belttensioning pulley; a hollow framestructure, said frame structure including wall means defining a cylinderhaving open ends and closed side walls and whose axis is parallel to thedirection of movement of said belttensioning pulley; a piston movable insaid cylinder and extending through one end thereof and terminatingwithin said cylinder and means connecting said piston to said belttensioning pulley whereby belt-tensioning force may be applied by movingsaid piston within said cylinder; said frame also including wall meansdefining a hollow box located at the other end of aid cylinder remotefrom said belt-tensioning device and communicating therewith; saidpiston having an internal chamber therein and a nut positioned in saidchamber at the end thereof adjacent said hollow box, said nut beingaxially, but not rotatably, movable within said chamber; a coil springpositioned within said chamber and hearing at one end thereof againstsaid nut and hearing at the other end thereof against the opposite endof said chamber; said hollow box having an opening in the end wallthereof opposite said other end of said cylinder and substantiallycoaxial therewith; a threaded rod extending through said opening andthreadedly engaging said nut whereby upon rotation of said rod said nutwill be moved axially within said chamber to adjust the tension exertedby said spring on said piston; said box having an opening through theside wall thereof; a manually rotatable shaft extending through saidlast-named opening and gearing connecting said shaft to said rod wherebysaid rod will be rotated upon rotation of said shaft.

2. In a belt-tensioning apparatus for a belt-type abrading machine, thecombination comprising: a movable belt tensioning pulley; a hollow framestructure, said frame structure including wall means defining a cylinderhaving open ends and closed side walls and whose axis is parallel to thedirection of movement of said belt-tensioning pulley; a piston movablein said cylinder and extending through one end thereof and terminatingwith said cylinder and means connecting said piston to said belttensioning pulley whereby belt-tensioning force may be applied by movingsaid piston within said cylinder; said frame also including wall meansdefining a hollow box located at the other end of said cylinder remotefrom said belt-tensioning device and communicating therewith; saidhollow box having an opening in the end wall thereof opposite said otherend of said cylinder; a block positioned within said box and sealinglycontacting said other end of said cylinder and closing oif the openingtherein at said one end; a bolt in said box and bearing against block,said bolt extending into said opening and a nut threadedly engaging saidbolt and bearing against said opposite end wall of said box whereby saidbolt may be adjusted to hold said block in position; said box having anopening through the side wall thereof; a fluid pressure conduitextending said last-named opening; said block having an openingtherethrough and means connecting said conduit to said opening wherebyfluid pressure may be applied to move the piston with said cylinder.

3. In a belt tensioning apparatus for a belt type abrad ing machine, thecombination comprising: a movable belt tensioning pulley; a hollow framestructure, said frame structure including wall means defining a cylinderhaving open ends and closed side walls and whose axis is parallel to thedirection of movement of-said belt tensioning pulley; a piston movablein said cylinder and extending through one end thereof and meansconnecting said piston to said belt tensioning pulley whereby belttensioning force may be applied by moving said piston within saidcylinder; a block sealingly contacting the other end of said cylinderand closing off the opening therein at said other end; means supportedon said frame and bearing against said block for holding said block inposition; a fluid pressure conduit extending through said frame; saidblock having an opening therethrough and means connecting said conduitto said opening whereby fluid pressure may be applied to move the pistonwithin the cylinder.

4. In belt tensioning apparatus for a belt-type abrading machine, thecombination comprising; a movable belttensioning pulley and a pistonconnected to said pulley, a frame for receiving said piston, said frameincluding wall means defining a cylinder having open ends. and closedside Walls and whose axis is parallel to the direction of movement ofsaid belt-tensioning pulley, said piston being slidably received in saidcylinder through one end thereof and terminating within said cylinder,said frame also including wall means defining a hollow box located atthe other end of said cylinder remote from said belttensioning pulleyand communicating therewith, said box having an opening in the end wallthereof opposite said other end of said cylinder and substantiallycoaxial therewith, said box having an opening through the side wallthereof, said openings in the walls of said box being adapted to receiveelements therethrough for moving said piston within said cylinder, saidpiston being round and having an axially extending slot in the side wallthere of in the portion thereof received within said cylinder, and a pinextending through a side wall of said cylinder and extending into saidslot for permitting axial movement of said piston within said cylinderbut preventing rotation of said piston with respect to said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS2,489,811 Perkins NOV. 29, 1949 FOREIGN PATENTS 16,756 Great BritainJan. 21, 1914-

